Detection of Fas and its ligand, FasL, in mouse thymus by in situ hybridization.

Part of the apoptotic process in lymphocytes involves the Fas receptor, which can transduce a cell death signal after interaction with its ligand, FasL. Many studies concerning expression of Fas and FasL in the thymus have been performed, but no detailed information about in situ expression patterns of mRNA inside the thymus is available. In the present study the expression of Fas and FasL was evaluated by non-radioactive in situ hybridization in the thymi of normal mice and compared with the results of lpr- and gld-mice, the two mouse models with mutations of Fas and FasL, respectively. In the thymi of normal and gld-mice, Fas mRNA was found only in the medulla. In lpr-mice, no Fas mRNA expression could be detected. The expression pattern changes as the mice get older. No specific signals for FasL mRNA were detected in any of the mice (normal, lpr, gld) tested. Together, these results are consistent with absence of a role for the Fas-FasL interaction in thymocyte apoptosis.